Refrigerated freight containers



March 30, 1965 P. TALMEY ETAL REFRIGERATED FREIGHT CONTAINERS 1 RM t mu m WT e VL a U m P h s s E I v on mm mm R 2 P UM D n 8 E 1 & vm B mm mm m 0M e m m L a mu 0 w m N E? March 30, 1965 P. TALMEY ETAL REFRIGERATED FREIGHT CONTAINERS United States Patent York Filed Oct. 12, 1962, Ser. No. 230,065 7 Claims. (Cl. 165-41) lChe present invention relates to refrigerated freight containers, and more particularly to such containers that may be readily converted into the body of a road semi-trailer for highway operation and into the body of a railway car for railway operation; and it is a general object of the invention to provide in the freight container of this type that is disclosed in the copending application of Ernest Freudman, Serial No. 215,095, filed August 6, 1962, now Patent No. 3,133,658, granted May 19, 1964, improved structure for reinforcing the composite base thereof.

Another object of the invention is to provide in a refrigerated freight container, structure that not only reinforces the composite base thereof, but that also provides a lading-supporting floor in the lading compartment thereof and that defines floor fiues therein so as to accommodate improved circulation of cooling air through the lading compartment to effect refrigeration of the lading therein.

A further object of the invention is to provide in a refrigerated freight container, a composite base of improved construction and arrangement that achieves great strength and rigidity therein and that provides a ladingsupporting fioor in the lading compartment thereof and that provides floor fiues therein for circulating the cooling air in the lading compartment.

A still further object of the invention is to provide in a refrigerated freight container, improved structure of the character described that may be readily installed into the base of the container after fabrication of the other component elements thereof and at small expense and in a simplified manner.

Further features of the invention pertain to the particular arrangement of the elements of the refrigerated freight container, whereby the above-outlined and additional operating features thereof are attained.

The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specification, taken in connection with the accompanying drawings, in which:

FIGURE 1 is a side elevational view of a refrigerated freight container embodying the present invention and illustrating the combination of the container with highway running gear to produce a road semi-trailer;

FIG. 2 is a side elevational view of two of the freight containers and illustrating the combination of the two containers with railway running gear to produce a composite body for a railway car;

FIG. 3 is an enlarged fragmentary horizontal sectional view of the freight container, this view being taken in the direction of the arrows along the line 3-3 in FIG. 1;

FIG. 4 is a greatly enlarged fragmentary lateral vertical sectional view of the freight container, this view being taken in the direction of the arrows along the line 4-4 in FIG. 3;

3,175,606 Patented Mar. 39, 1965 ICC FIG. 5 is an enlarged fragmentary longitudinal vertical sectional view of the freight container, this view being taken in the direction of the arrows along the line 5-5 in FIG. 3; and

FIG. 6 is a still further enlarged fragmentary view of the lower right-hand portion of FIG. 4, this view being taken within the ring 6, as shown in FIG. 4.

Referring now to FIGS. 1 and 2 of the drawings, the several identical freight containers 51) there illustrated, and embodying the features of the present invention, are adapted to be employed in freight transportation systems of the highway-railway-waterway type. Specifically, the container 50 may be combined with highway running gear to produce a road semi-trailer, as shown in FIG. 1; two of the containers 50 may be combined with railway running gear to produce a composite body for a railway car, as shown in FIG. 2; and a great plurality of the containers 50 may be suitably stored in the hold of a ship, not shown, to compartmentize the same in an obvious manner. Specifically, the container 50 comprises a rigid base 51 carrying on the top thereof a substantially box-like body 52. Also, the front central bottom portion of the base 51 carries a downwardly directed kingpin 53 and the rear side bottom portions of the base 51 respectively carry longitudinally extending downwardly directed rail-like structure 54.

When the container 50 is adapted for highway transportation, as shown in FIG. 1, the kingpin 53 thereof is coupled to a conventional fifth-wheel mechanism 61 carried by the rear end of a conventional road tractor 62, the fifth wheel mechanism 61 being of the elevator type selectively movable between a lower road-traveling position and an upper transfer position in the usual manner. Also, the fifth-wheel mechanism 61 is selectively operable to couple and to uncouple the kingpin 53 in the usual manner. Moreover, the structures 54 are connected to a conventional road bogie 63 of the usual road-wheel type. Thus, the container 50 and the road bogie 63 cooperate to produce a road semi-trailer.

When the containers 50 are adapted for railway transportation, as shown in FIG. 2, the respective bases 51 of two of the containers 50 are mounted upon the opposite top ends of the frame 71 of a cooperating railway car '70. Preferably, the railway car is of the construction and arrangement of that disclosed in the copending application of Deodat Clejan, Serial No. 151,358, filed November 9, 1961, now Patent No. 3,102,646, granted September 3, 1963; which railway car 70 is of skeleton-like construction in that the frame 71 thereof consists essentially of an elongated beam or center sill arranged in bridging relation with a pair of longitudinally spaced-apart trucks 72 provided with flanged track wheels 73 engaging the rails of an associated railway track indicated at 74. Also, as best shown in FIG. 2, the opposite outer sides of the beam or center sill 71 respectively carry elongated longitudinally extending members 75, two of such members 75 being independently resiliently mounted upon each side of the center sill 71 and disposed in longitudinal alignment with each other. Also, the center sill 71 essentially comprises two longitudinally extending and laterally spaced-apart I-beams 76 and is of fish-belly construction. Thus, the top flanges 77 of the I-beams 76 constitute the respective rails of a narrow gauge track provided upon the top side edges of the center sill 71 and disposed, together with the members 75, well inwardly with respect to the inner sides of the track wheels 73 carried by the trucks 72. Each of the members 75 is disposed below the adjacent top flange 77 of the associated I-beam 76, and also projects laterally outwardly somewhat beyond the adjacent top flange 77, so that the members 75 are readily accessible from the top sides of the center sill 71 for a securing purpose, and further the members 71 perform a shock-absorbing purpose; all as explained more fully below.

Preferably, each of the containers 50 is mounted upon the top of the railway car 70 employing a laterally ,ex tending front bolster 81 and a laterally extending rear bolster 82 of the construction and arrangement of that disclosed in the copending application of Robert L. Hassen-auer and Samuel H. Enochian, Serial No. 209,946, filed July 16, 1962. More particularly, the front end of the base 51 is supported by the front bolster 81 disposed therebelow and the rear end of the base 51 is supported by the rear bolster 82 disposed therebelow, the bolsters 81 and 82 being individually removably supported upon the top flanges 77 of the I-beams 76 in longitudinally spaced-apart relation. The front bolster 81 is selectively secured in place in its supported position upon the top flanges 77, and in turn, is selectively locked to the adjacent bottom front end of the supported base 51; and similarly, the rear bolster 82 is selectively secured in place in its supported position upon the top flanges 77, and in turn, is selectively locked to the adjacent bottom rear end of the supported base 51. The bolsters 81 and 82 in their mounted and secured positions and the base 51 in its mounted and locked position are movable longitudinally along the top flanges 77, as permitted by the members 75. More particularly, as indicated in FIG. 2, the front bolster 81 is free to move along the top flanges 77, while the rear bolster 82 carries structures 83 on the opposite end-s thereof that project downwardly therefrom into cooperating and connecting relation with the members 75 respectively carried by the opposite sides of the center sill 71, whereby the members 75 allow only limited and cushioned longitudinal movements of the mounted unit with respect to the center sill 71, and whereby the members 75 prevent the transmission of severe longitudinal shock-s from. the center sill 71 to the connected container 50. In the railway car 70, the members 75 are respectively mounted upon the opposite sides of the center sill 71 by a plurality of longitudinally spaced-apart blocks, not shown, of elastomeric material, such for example, as rubber; whereby the movements of each member 75 relative to the center sill 71 are not only cushioned, as previously noted, but are also damped, so that the members 75 serve the shock-absorbing function. Hence, the members 75 serve the resilient cushioning function, the shock absorbing function and the securing function be tween the center sill 71 of the railway car 70 and the mounted container 50. In passing, it is noted that the two containers 50 mounted upon the top of the center sill 71, as shown in FIG. 2, are independently resiliently mounted and secured in place by the two pairs of members 75 respectively carried by the opposite ends of the center sill 71 upon the respective opposite sides thereof. The containers 50 may be loaded and unloaded with respect to the railway car 70 in any suitable manner, such, for example, as by the utilization of an overhead gantry crane, not shown, as disclosed in the previously mentioned application of Hassenauer and Enochian.

Referring now to FIGS. 3 to 6, inclusive, the container 50 is of the fundamental construction and arrangement of that disclosed in the previously mentioned copending application of Ernest Freudman; whereby the base 51 of the container 50 is of elongated rectangular form including a pair of longitudinally extending side sills 91, a laterally extending front end sill 92 and a laterally extending rear end sill 93. The front ends of the side sills 91 are respectively rigidly joined to the adjacent ends of the front end sill 92. by a pair of angularly disposed upstanding-plates 94, while the rear end sill 93 is arranged between the rear ends of the side sills 91 and rigidly joined thereto. The intermediate portions of the side sills 91 are rigidly tied together by a laterally extending intermediate sill 95 arranged therebetween and rigidly joined thereto. The side sills 91 comprise special sections, as best shown in FIG. 6; whereby each of the side sills 91 comprises an upstanding web 96 terminating at the lower end thereof in a laterally extending flange 97, an inwardly and laterally directed ledge 98 carried by the intermediate portion of the web 96, and an outwardly and laterally directed and downwardly turned bumper element 99 carried by the intermediate portion of the Web 96. The rear end portions of the flanges 97 of the side sills 91 constitute the previously mentioned structures 54 to which the road bogie 63 is selectively connected, as previously explained; whereby a longitudinally spaced-apart series of holes, not shown, are provided in each of the flanges 97 for the purpose of accommodating the securing of the road bogie 63 in place to the structures 54 at any one of a plurality of longitudinally spaced apart positions with respect to the rear end of the base 51. Also, the front end sill 92 carries an upstanding end plate 100, that, in turn, carries two vertically spaced-apart laterally extending and forwardly projecting bumper elements 101.

The front end of the base 51 is especially reinforced due to the selective support thereof by the fifth-wheel mechanism 61 carried by the rear end of the road tractor 62; and more particularly, a laterally extending intermediate sill 102 is disposed rearwardly of the front end sill 92 and between the adjacent end portions of the side sills 91 and rigidly secured thereto. The area of the front end of the base 51 difined between the front end sill 92 and the intermediate sill 102 and the adjacent front end portions of the side sills 91 is reinforced by a number of laterally extending and longitudinally spaced-apart framing members 103 to 107 inclusive, as shown in FIG. 5. The framing members 105 and 106 coooperate to define a pocket therebetween into which is securely fastened in place a removable block 108 that carries the previously described depending kingpin 53. The framing members 103 to 107, inclusive, are enclosed by top and bottom plates 109 and 110 respectively carried by the corresponding portions of the front end of the base 51. The top plate 109 extends longitudinally between the top of the front end sill 92 and the topof the intermediate sill 102 and extends laterally between the adjacent front end portions of the side sills 91 and is rigidly secured in place thereupon. The bottom end plate 110 extends longitudinally between the bottom of the end sill 92 and the bottom of the intermediate sill 102 and extends laterally between the adjacent front end portions of the side sills 91 and is rigidly secured in place thereupon. Also, the bottom end'plate 110 has an opening therein accommodating placement and removal therethrough of the kingpin block 108. When the front end of the base 51 is supported by the fifth-wheel mechanism 61 carried by the rear end of the road tractor 62, as shown in FIG. 1, the fifth-wheel mechanism 61 directly engages the bottom plate 110 and selectively couples and uncouples the kingpin 53 carried by the block 108 securely fastened in place in the pocket defined between the framing members 105 and 106.

The rear end of the base 51 is also especially reinforced; and more particularly, a laterally extending intermediate sill 111 is disposed forwardly of the rear end sill 93 and between the adjacent end portions of the side sills 91 and rigidly secured thereto. The rear end of the base 51 defined between the rear sill 93 and the intermediate sill 111 is enclosed by a rear top plate 112 and a rear bottom plate 113, the rear top plate 112 extending longitudinally between the top of the rear end sill 93 and the top of the intermediate sill 111 and laterally between the adjacent rear end portions of the side sills 91 and rigidly secured in place thereupon, and the rear bottom plate 113 extending longitudinally between the bottom of the rear end sill 93 and the bottom of the intermediate sill 111 and laterally '5 between the adjacent rear end portions of the side sills 91 and rigidly secured in place thereupon. Also, a laterally extending bumper element 114 is rigidly secured to the rear end sill 93 and projects longitudinally rearwardly therefrom.

Further, the front and rear ends of the base 51 respectively carry two pairs of laterally spaced-apart bottom connecting holes, not shown, that are employed in securing the corresponding ends thereof to the bolsters 81 and 82, as shown in FIG. 2.

As best shown in FIG. 6, two side plates 115 are respectively carried by the side sills 91, each of the side plates 115 being of substantially L-shape including a substantially vertically disposed flange 116 and a substantially horizontally disposed flange 117. The lower portion of the vertical flange 116 is suitably secured to the upper portion of the web 96 of the side sill 91 by a series of rivets 118, and the outer portion of the horizontal flange 117 is suitably secured to the ledge 98 carried by the web 96 of the side sill 91 by a series of bolts 119 provided with cooperating nuts. Also, the upper portion of the vertical flange 116 of the side plate 115 carries a bumper element 120. Further, as best shown in FIG. 5, a rear plate 121 is carried by the top of the rear end sill 93 and rigidly secured thereto, the rear plate 121 being substantially Z-shaped in cross section. In the arrangement the front plate 100, the rear plate 121 and the pair of side plates 115 cooperate to define an upstanding substantially rim-like structure carried by the base 51.

Referring now to FIGS. 4-, and 6, the base 51 further comprises a floor panel 130 of unitary rigid composite sandwich construction and arranged within the rim-like structure defined by the previously noted elements 100, 121 and 115. Specifically, the floor panel 130 extends longitudinally substantially between the front plate 100 and the rear plate 121 and extends laterally substantially between the side plates 115. More particularly, as shown in FIG. 5, the extreme front end of the floor panel 130 terminates adjacent to the front plate 100 and the front end portion of the floor panel 130 is supported by the front top plate 109. The extreme rear end of the floor panel 130 terminates adjacent to the rear plate 121 and the rear end portion of the floor panel 130 is supported by the rear top plate 112. As best shown in FIGS. 4 and 6, the opposite sides of the floor panel 130 respectively terminate adjacent to the side sills 91 and the side portions thereof are respectively supported by the horizontal flanges 117 of the side plates 115. Also, the intermediate portion of the fioor panel 130 is supported upon the top of the intermediate sill 95.

As best shown in FIG. 6, the floor panel 130 essentially comprises a top sheet 131 formed of a suitable aluminum alloy and having a thickness of about 0.025, an upper sheet 132 formed of fir plywood and having a thickness of about A", an upper layer 133 formed of synthetic organic resin of cellular structure, such, for example, as foamed polystyrene, and having a thickness of about 2", an intermediate sheet 134 formed of fir plywood and having a thickness of about A", a lower layer 135 formed of synthetic organic resin of cellular structure, such, for example, as foamed polystyrene, and having a thickness of about 2", a lower sheet 136 formed of fir plywood and having a thickness of about A, and a bottom sheet 137 formed of a suitable aluminum alloy and having a thickness of about 0.025". In the composite sandwich: the adjacent surfaces of the elements 131 and 132 are intimately secured together by an intervening layer of cement indicated at 131a, the adjacent surfaces of the elements 132 and 133 are intimately secured together by an intervening layer of cement indicated at 132a, the adjacent surfaces of the elements 133 and 134 are intimately secured together by an intervening layer of cement indicated at 133a, the adjacent surfaces of the elements 134 and 135 are intimately secured together by an interven- 6 ing layer of cement indicated at 134a, the adjacent surfaces of the elements 135 and 136 are intimately secured together by an intervening layer of cement indicated at 135a, and the adjacent surfaces of the elements 136 and 137 are intimately secured together by an intervening layer of cement indicated at 136a; which layers 131a, etc., may be formed of a suitable epoxy resin cement.

The elements 131 and 137 being formed of metal serve to prevent penetration of the interior of the floor panel 130 by Water, moisture, etc., either from the inside of the body 52 or from the exterior thereof, the element 137 constituting the usual exterior weather sheet in the floor panel 130.

The composite floor panel 130 is securely fastened to the supporting elements 100, 121 and of the base 51, as explained more fully hereinafter; whereby the floor panel constitutes the fundamentally strong rigid structural element that is incorporated in the base 51.

Referring now to FIGS. 3 to 6, inclusive, the body 52 of the container is of strong rigid unitary structure comprising, in addition to the floor panel 130, a ceiling or roof panel 149, a pair of front side wall panels 141, a pair of rear side wall panels 142 and a bulkhead panel 143 cooperating with each other to define a lading compartment 144 in the central portion and in the rear end portion of the container 50. Each of the panels 140, 141, 142 and 143 is of rigid compo-site sandwich construction, as disclosed in the previously mentioned application of Ernest Freudman, whereby the lading compartment 144 is heat-insulated by the body 52 of the container 50. Each front side wall panel 141 cooperates with the adjacent rear side wall panel 142 to define an upstanding side doorway in the corresponding side of the body 52 and communicating with the corresponding side of the lading compartment 144; which side doorway is provided with a pair of cooperating side doors 145 and 146. Also the rear ends of the floor panel 130, the roof panel and the rear side Wall panels 142 cooperate with each other to define an upstanding rear doorway in the rear end of the body 52 and communicating with the rear end of the lading compartment 144; which rear doorway is provided with a pair of cooperating rear doors 147 and 148. Also the side doors and 146 and the rear doors 147 and 148 are of rigid composite sandwich construction, as disclosed in the previously mentioned application of Ernest Freudman.

Further, the container 50 comprises a front end wall panel 150 and a pair of dividing wall panels 151 and 152 that cooperate with each other to define a centrally disposed plenum chamber 153 and flue chamber 154 in the front end of the body 52, the two chamhers 153 and 154 being disposed in upper and lower positions and separated from each other by a horizontal baffle 155, as best shown in FIG. 5. Each of the panels 159, 151 and 152 is also of rigid composite sandwich construction, as disclosed in the Freudman application. Further, the panels 130, 141 143 and 151 cooperate with each other to define a machinery compartment 156 disposed in one front corner of the body 52 and arranged exteriorly of the lading compartment 144 and the chambers 153 and 154; and, similarily, the panels 130, 140, 143 and 152 cooperate with each other to define a fuel tank storage compartment 157 disposed in the other front corner of the body 52 and arranged exteriorly of the lading compartment 144 and the chambers 153 and 154. The front end of the machinery compartment 156 is closed by a plate 158, while the outer side thereof is open; and, likewise, the front end of the fuel storage compartment 157 is closed by a plate 159, while the outer side thereof is open. The outer side of the machinery compartment 156 is suitably framed by structure, including an upstanding corner post 161, so as to provide an outer side doorway 162 thereinto; and similarly, the outer side of the fuel storage compartment 157 is suitably framed by structure,

including an upstanding corner post'163, so as to provide an outer side doorway 164 thereinto.

In the body 52 the various panels 130, 140, 141, 142, .143, 150, 151 and 152 are rigidly secured together and to associated framing structure so as to lend great strength and rigidity to the body 52. For example, the front end of the floor panel 130 is secured to the front plate 180 and to the bottom of the front end panel 150 by a body of resin .171; the rear end of the floor panel 138 is secured to the rear plate 121 by a wooden timber 172; and the sides of the floor panel 130 are secured to .the adjacent bottoms of the side panels 141 and 142 by bodies of resin 173. Similarly, the front end of the roof panel 140 is secured to the top of the front end panel 150 by a body .of resin 174; the rear end of the roof panel 140 is secured to a top Wooden framing timber 175 :by a body of resin 176; and the sides of the roof panel 140 are secured to the adjacent tops of the side panels 141 and'142 by bodies of resin, not shown, The bcdles' of resin 171, etc., mentioned may comprise foamed polyurethane, whereby these bodies effect both thesecuring function and a heat-insulating function.

The machinery compartment 156 is adapted to receive a refrigerating machine of the compressor-condenser evaporator type and provided with an internal combustion engine for driving the compressor; which apparatus comprises a unit that is removable with respect to the machinery compartment 156; which apparatus is so constructed and arranged that the evaporator thereof projects through an opening 1a provided in the di viding wall panel 151 into the plenum chamber 153, when the unit occupies its normal position in the ma chinery compartment 156; and which unit further plugsthe remainder of the opening 151a so as to close the plenum chamber 153 from the machinery compartment 156 and to heat-insulate the same from each other. Also, the evaporator of the refrigerating machine comprises a blower for circulating air between the lading compartment 144 and the plenum chamber 153, as explained more fully hereinafter. Further, the internal combustion engine of the unit may operate using propane as a fuel; whereby fuel tanks containing compressed and liquified propane are. removably arranged in the fuel tank storage compartment 157 and operatively connected to the internal combustion engine, when the unit occupies its normal position in the machinery compart' men: 156. i

More particularly, upper and lower openings 143a and 14312 are respectively arranged in the corresponding central portions of the bulkhead panel 143; a flue or con duit 177 is arranged in the flue chamber 154 and con nected between an opening 155a provided in the baffle 155 and the opening 14311 formed in the bulkhead panel 143. Also a pair of bafile sheets 147a and 148a are respectively carried by the inner surfaces of the rear doors 147 and 148, thereby to provide two corresponding upstanding rear flues 147b and 14812 at the rear end of the landing compartment 144, when the rear doors 147 and 148 occupy their normal closed positions. Thus, it will .be understood that operation of the blower car ried by the evaporator of the refrigerating machine effects the circulation of air from the top of the plenum chamber 153 through and into heat-exchange relation with the evaporator and thence through the opening 155a, the conduit 177 and the opening 143b onto the top of the floor panel 130 in the front end of the lading compartment 144; the cool air then proceeds rearwardly along the floor panel 130 through the lading compartment 144 and thence upwardly through the tines 147b and 148i) defined in the rear doors 147 and 148, and thence forwardly along the roof panel 140 through the lading cornpartnrent 144; and ultimately the air passes through the opening 143a and back into the top of the plenum chamber 153; all as shown in FIG. 5.

Referring now to FIGS. 3 to 6, inclusive, in accord ance with the present invention, the composite base 51 oft he container 50 is further strengthened and reinforced adjacent to the intermediate and rear end portions there of by a pair of longitudinally extending and laterally spacedapart structural elements 181 respectively disposed :adjacent to the opposite sides of the floor panel 131 at the respective junctions thereof with the pairs of side wall panels 141 and 142, a pair of longitudinally extending structural elements 182 respectively arranged inwardly adjacent to the elements 181, and a plurality of longitudinally extending and laterally spaced-apart structural elements 183 arranged between the elements 182. The elements 181 are L-shaped; the elements 182 are U-shaped; and the elements 183 are Z-shaped; whereby the elements 181, 1 82 and 183 cooperate with each other to define both a lading-supporting floor in the lading compartment 144 and a plurality of floor lines 184 there hetwen and extending longitudinally substantially from end to end of the 'lading compartment 144. The elements 181 extend the entire length of the lading compartment 144, While the elements 182 and 184 extend -from a position disposed somewhat rearwardly of the inner side of the bulkhead panel 143 to a position disposed somewhat forwardly of the inner sides of the rear doors 147 and 148, as best shown in FIG. 5; whereby :the elements 182 and 133 span substantially the length of the intermediate portion of the floor panel disposed between the front and reinforcement of the composite base 51, produced by the intermediate sill 102, etc, and the rear end reinforcement of the composite base 51, produced by the intermediate sill 111, etc. Thus, the front end portion reinforcement and the rear end portion reinforcement of the composite base 50 are efcfiected from below the floor panel 130, while the intermediate portion rcinforcerncnt of the composite base 50 is effected from above the floor panel 130. This arrangeunent is very advantageous, since the elements 181, 182 and 183 being positioned on top of the floor panel 130 not only produce the required reinforcement of the composite .base 51, but they also establish the lading-supporting floor in the lading compartment 144 and define the sheer ilues 184.'

g The elements 181 are rigidly secured to the adjacent portions of the panels 130 and 141 and 142 utilizing a respective series of fasteners 185 and 186; and the elements 182 and 183 are rigidly secured to the floor panel 130 utilizing respective series of fasteners 187 .and 188. Also, a plurality of laterally extending and longitudinally spaced apart straps 189 are carried by the top elements 181, 182 and 1 83; which straps 18? are suitably secured in place with respect to the elements 181, 182

:and 183 in order to integrate the reinforcement of the intermediate and rear end portions of the composite base 51 into a unitary structure. Thus, the elements 181, 182 and 183 and the straps 189 lend great rigidity to composite base 51.

Again referring to FIG. 5, will be observed that the cool air issuing through the bottom opening 143k formed in the bulkhead panel 143 proceeds rearwardly into the front ends of the floor flues 184, and that the air flows rearwardly through the floor flues 184 past the areas of the side doorways and then from the rear ends of the floor fiues 184 and thenupwardly through the rear door flues 147b and 14811.

In a constructional example .of the container50, the

same may have a maximum outside width of 79%,

occupies its mounted position upon the railway car 70,

9 employing the bolsters 81 and 82, as shown in FIG. 2, the maximum clearance height between the tops of the track rails 74 and the top of the body 52 of the container 50 is 128 The other dimensions of the container 50 are generally related to those set forth in accordance with the scales of the difierent figures of the drawings.

In the container 50, the floor panel 130 is of block-like configuration having a length (X) of 397 /2", a width (Y) of 74% and a thickness (Z) of 4.8"; whereby the floor panel 130 has a length X that is in excess of about 30 feet and a width Y that is in excess of about 6 feet and a thickness Z that is in excess of about 4 inches. In the fioor panel 130, each of the inner liner sheet 131 and the other weather sheet 137 is preferably formed of a suitable aluminum alloy, as previously noted, but the same may be formed of steel, including stainless steel; and ordinarily the gauge thereof is within the general range 20 to 100 mils, 0.025" aluminum sheet being entirely satisfactory, as previously noted. Of course, additional strength may be imparted to the floor panel 130 by increasing the thickness of each of the plywood sheets 132, 134 and 136; however, the use of A" fir plywood for this purpose is altogether adequate. Similarly, the k factor of the floor panel 130 may be further reduced by increasing the thickness of each of the slabs 133 and 135, but here again little advantage is gained since the floor panel 130 already has an exceedingly low k factor employing the foamed polystyrene slabs 133 and 135 each of a thickness of 2".

At this point, it is noted that the peculiar arrangement of th e elements 132, 133, 134, 135 and 136 in the floor panel 130 is productive of a stiffness therein that greatly exceeds that obtained by the mere sandwich utilization of such materials of equivalent thicknesses. Specifically, a reference sandwich construction of 5-ply might comprise an outer weather sheet of aluminum of 0.025", an adjacent outer fir plywood sheet of a foamed polystyrene core of 4", an adjacent inner fir plywood sheet of and an inner liner sheet of aluminum of 0.025"; which reference sandwich of 5-ply has equivalent thicknesses of materials as the present sandwich of 7-ply, as disclosed heretofore; however, this reference sandwich of S-ply is not nearly as stiff as the present sandwich of 7-ply. In other words, the present sandwich of 7-ply achieves a synergistic result with respect to stiffness in the present peculiar distribution of the same materials in the same total thicknesses; which increased stiffness is obtained without substantial increase in manufacturing costs of the floor panel 130 and with no particular increase in the weight thereof. Also, the present sandwich of 7-ply has a k factor that is somewhat lower than that of the reference panel of S-ply, as described above. Hence, the present sandwich of 7-ply is productive of unique and unexpected characteristics with respect to those of the above described reference panel of S-ply; and while the improved mode of the present sandwich of 7-ply is not altogether understood, it is none the less emphatic.

In the structure of the container 50, where materials of construction are not specifically designated, it will be understood that suitable materials of construction may be employed; however, steel is such suitable material of construction of a majority of the structural elements of the container 50, as herein disclosed.

In view of the foregoing, it is apparent that there has been provided a refrigerated freight container that is selectively adapted for highway operation and railway operation and that is of strong unitary construction and arrangement. The fundamentally strong and rigid structural member of the container that contributes so greatly to the overall strength and rigidity thereof, is the floor panel thereof, that is of the peculiar sandwich construction, as previously described; however, the roof panel and the side wall panels, as well as the front end wall panel and the bulkhead wall panel and the dividing wall panels, all of strong rigid sandwich construction, materially contribute to the total strength and rigidity of the container. Further, another feature of construction of the container that is of substantial importance with reference to the strength and rigidity thereof, concerns the arrangement wherein both the floor panel and the roof panel run from end to end thereof and beyond the lading compartment and respectively under and over both the machinery compartment and the fuel tank storage compartment and the plenum chamber formed in the front end of the body of the container, and notwithstanding the circumstance that the floor panel and the roof panel perform no particular useful heat-insulating functions with respect to these two compartments, but which arrangement is most advantageous to obtain maximum strength and rigidity in the container. Another important feature of construction of the container thus provided resides in the circumstance that the individual panels incorporated in the body thereof not only achieve great strength and rigidity in the body thereof, but are individually of exceedingly light weight and have an excellent heat-insulating characteristic; whereby a very low U factor is automatically achieved for the lading compartment defined in the body of the container by the assembly of the panels described, each having not only great strength and rigidity, but also an exceedingly low k factor. Still another important feature of construction of the floor panel resides in the utilization of the reinforcing members upon the top thereof; wherein these members not only perform the reinforcing function mentioned, but they define the ladingsupporting floor in the lading compartment and the floor flues therein for confining the circulated cooling air in the lading compartment.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be understood that various modifications may be made therein, and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

What is claimed is:

l. A refrigerated freight container comprising an elongated substantially rectangular base frame including a pair of longitudinally extending side sills and a pair of laterally extending end sills, the opposite ends of said end sills being rigidly secured to the corresponding opposite ends of said side sills, a first laterally extending intermediate sill arragned within the front end portion of said base frame and located rearwardly of the front one of said end sills, the opposite ends of said first intermediate sill being rigidly secured to the adjacent front portions of said side sills, a front plate carried by the top front end portion of said base frame and extending longitudinally between said front end sill and said first intermediate sill and rigidly secured thereto and also extending laterally between the front portions of said side sills and rigidly secured thereto, thereby to reinforce the front end portion of said base frame, a second laterally extending intermediate sill arranged within the rear end portion of said base frame and located forwardly of the rear one of said end sills, the opposite ends of said second intermediate sill being rigidly secured to the adjacent rear portions of said side sills, a rear plate carried by the rear end portion of said base frame and extending longitudinally between said rear end sill and said second intermediate sill and rigidly secured thereto and also extending laterally between the rear portions of said side sills and rigidly secured thereto, thereby to reinforce the rear end portion of said base frame, an elongated substantially rectangular floor panel of prefabricated unitary rigid sandwich structure arranged upon the top of said base frame with the lower front portion of said floor panel supported upon the top of said front plate and with the lower rear portion of said floor panel supported upon the top of said rear plate, the opposite sides of said floor panel being securely 11 fastened to said side sills and the 'opposite'ends of said floor panel being securely fastened to said end sills, whereby said base frame and said floor panel cooperateto produce a composite base with said floor panel lending great rigidity thereto, an upstanding laterally extending substantially rectangular heat-insulating bulkhead carried by the front end portion of said floor panel and rigidly secured thereto, said bulkhead being located approximately above said first intermediate sill, first heat-insulating structure rigidly secured to said composite base and located rearwardly of said bulkhead and cooperating mutually therewith to produce a substantially box-like body defining a lading compartment therein that is disposed above both the central portion and the rear end portion of said composite base, second heat-insulating structure rigidly secured to said composite base and located forwardly of said bulkhead and cooperating mutually therewith to produce a substantially box-like housing defining a plenum chamber therein that is disposed above the front end portion of said composite base, a plurality of longitudinally extending rigid structural members arranged in laterally spaced-apart relation and securely fastened to the top of said floor panel, at the central and rear end portions thereof, thereby to reinforce the corresponding central and rear end portions of said composite base, said structural members being disposed in said lading compartment and cooperating with each other to define in said lading compartment both a lading-supporting floor and a plurality of longitudinally extending and laterally spaced-apart floor flues, said lading supporting floor and said floor flues being positioned above the top of said floor panel, means for circulating aid from said plenum chamber through a bottom opening provided in said bulkhead and thence rearwardly through said floor flues in said lading compartment and then upwardly and back forwardly through the upper portion of said lading compartment and ultimately back through a top opening provided in said bulkhead and thus back into said plenum chamber, and means disposed in said plenum chamber for cooling the air that is circulated therethrough.

2. The refrigerated freight container. set forth in claim 1, wherein each of said structural members includes an upstanding web carrying top and bottom flanges, said bottom flanges are securely fastened to the top of the central portion and the rear end portion of said floor panel, said top flanges define said lading-supporting floor, and said floor flues are defined between said webs.

3. The refrigerated freight container set forth in claim 1, wherein each of said structural members essentially comprises a Z-shaped member including an upstanding web carrying top and bottom flanges, said bottom flanges are securely fastened to the top of the central portion and the rear end portion of said floor panel, said top flanges define said lading-supporting floor, and said floor flues are defined between said Webs.

4. The refrigerated freight container set forth in claim 1, wherein said structural members are spaced-apart laterally so as to provide a plurality of longitudinally extending slots communicating through said lading-supporting floor between the topsof said floor flues and the bottom of said lading compartment.

5. A refrigerated freight container comprising an elongated substantially rectangular base frame including a pair of longitudinally extending side sills and a pair of laterally extending end sills, the opposite ends of said end sills being rigidly secured to the corresponding opposite ends of said side sills, a first laterally extending intermediate sill arranged Within the front end portion of said base frame and located rearwardly of the front one ofsaid end sills, the opposite ends of said first intermediate sill being rigidly secured to the adjacent front portions of said side sills, a front plate carried by the top front end portion of said base frame and extending longitudinally between said front end sill and said first intermediate sill and rigidly secured thereto and also extending laterally between the front portions of said side sills and rigidly secured thereto, thereby to reinforce the front end portion of said base frame, a second laterally extending intermediate sill arranged within the rear end portion of said base frame and located forwardly of the rear one of said end sills, the opposite ends of said second intermediate sill being rigidly secured to the adjacent rear portions of said side sills, a rear plate carried by the rear end portion of said base frame and extending longitudinally between said rear'end sill and said second intermediate sill and rigidly secured thereto and also extending laterally between the rear portions of said side sills and rigidly secured thereto, thereby to reinforce the rear end portion of said base frame, an elongated substantiallyrectangular floor panel of prefabricated unitary rigid sandwich structure arranged upon the top of said base frame with the lower front portion of said floor panel supported upon the top of said'front plate and with the lower rear portion of said fioor panel supported upon the top of said rear plate, the opposite sides of said floor panel being securely fastened to said side sills and the opposite ends of said floor panel being securely fastened to said end sills, whereby said base frame and said floor panel cooperate to produce a composite base with said floor panel lending great rigidity thereto, an upstanding laterally extending substantially rectangular heat-insulating bulkhead carried by the front end portion of said floor panel and rigidly secured thereto, said bulkhead being located approximately above said first intermediate sill, first heat-insulating structure rigidly secured to said composite base and located rearwardly of said bulkhead and cooperating mutuallytherewith to produce a substantially box-like body defining a lading compartment therein that is disposed above both the central portion and the rear end portion of said composite base, second heat-insulating structure rigidly secured to said composite base and located forwardly of said bulkhead and cooperating ,mutually therewith to produce a substantially box-like housing defining a plenum chamber therein that is disposed above the front end portion of said composite base, a plurality of longitudinally extending rigid structural members arranged in laterally spaced-apart relation and engaging and secured to the top of said floor panel at the central and rear end portions thereof, a plurality of laterally extending straps arranged in longitudinally spacedapart relation and engaging and secured to the tops of said structural members, thereby to reinforce the corresponding central and rear end portions of said composite base, said structural members and said straps being disposed in said lading compartment and cooperating mutually with each other to define in said lading compartment both a lading-supporting floor and a plurality of longitudinally extending and laterally spaced-apart floor flues, said lading supporting floor and said floor flues being positioned above the top of said floor panel,- means for circulating air from said plenum chamber through a bottom opening provided in said bulkhead and thence 'rearwardly through said floor fiues in said lading compartment and then upwardly and backforwardly-through the upper portion of said lading compartment and ultimately back through a top opening provided in said bulkhead and thus back into said plenum chamber, and means disposed in said plenum chamber for cooling the air that is circulated therethrough.

6. A refrigerated freight container comprising an elongated substantially rectangular base frame including a pair of longitudinally extending side sills and a pair of laterally extending end sills, the opposite ends of said end sills being rigidly securedto the corresponding opposite ends of said side sills, a first laterally extending intermediate sill arranged within the front end portion of said base frame and located rearwardly of the front one of said end sills, the opposite ends of said first intermediate sill being rigidly secured to the adjacent front portions of said side sills, a front plate carried by the top 13 front end portion of said base frame and extending longitudinally between said front end sill and said first intermediate sill and rigidly secured thereto and also extending laterally between the front portions of said side sills and rigidly secured thereto, thereby to reinforce the front end portion of said base frame, a second laterally extending intermediate sill arranged within the rear end portion of said base frame and located forwardly of the rear one of said end sills, the opposite ends of said second intermediate sill being rigidly secured to the adjacent rear portions of said side sills, a rear plate carried by the rear end portion of said base frame and extending longitudinally between said rear end sill and said second intermediate sill and rigidly secured thereto and also extending laterally between the rear portions of said side sills and rigidly secured thereto, thereby to reinforce the rear end portion of said base frame, an elongated substantially rectangular floor panel of prefabricated unitary rigid sandwich structure arranged upon the top of said base frame with the lower front portion of said fioor panel supported upon the top of said front plate and with the lower rear portion of said floor panel supported upon the top of said rear plate, the opposite sides of said floor panel being securely fastened to said side sills and the opposite ends of said fioor panel being securely falstened to said end sills, whereby said base frame and said floor panel cooperate to produce a composite base with said floor panel lending great rigidity thereto, an upstanding laterally extending substantially rectangular heatinsulating bulkhead carried by the front end portion of said floor panel and rigidly secured thereto, said bulkhead being located approximately above said first intermediate sill, first heat-insulating structure rigidly secured to said composite base and located rearwardly of said bulkhead and cooperating mutually therewith to produce a substantially box-like body defining a l-ading chamber therein and provided with a rear doorway communicating with the rear end of said lading compartment, said lading compartment being disposed above both the central portion and the rear end portion of said composite base, a pair of heat-insulating rear doors respectively mounted upon the opposite rear sides of said body for pivoted movements relative thereto and with respect to said rear doorway, said rear doors being movable inwardly into closed positions disposed within said rear doorway and movable outwardly into open positions removed from said rear doorway, second heat-insulating structure rigidly secured to said composite base and located forwardly of said bulkhead and cooperating mutually therewith to produce a substantially box-like housing defining a plenum chamber therein that is disposed above the front end portion of said composite base, a plurality of longitudinally extending rigid structural members arranged in laterally spaced-apart relation and securely fastened to the top of said floor panel at the central and rear end portions thereof, thereby to reinforce the corresponding central and rear end portions of said composite base, said structural members being disposed in said lading compartment and cooperating with each other to define in said lading compartment both a ladingsupporting floor and a plurality of longitudinally extending and laterally spaced-apart floor fiues, said lading supporting floor and said floor flues being positioned above the top of said floor panel, the front ends of said structural members terminating somewhat rearwardly of said bulkhead and the rear ends of said structural members terminating somewhat forwardly of said rear doors when they are in their closed positions, means for circulating air from said plenum chamber through a bottom opening provided in said bulkhead and thence rearwardly through said floor fiues in said lading compartment and then upwardly and back forwardly through the upper portion of said lading compartment and ultimately back through a top opening provided in said bulkhead and thus back into said plenum chamber, and means disposed 14 in said plenum chamber for cooling the air that is circulated therethrough.

7. A refrigerated freight container comprising an elongated substantially rectangular base frame including a pair of longitudinally extending side sills and a pair of laterally extending end sills, the opposite ends of said end sills being rigidly secured to the corresponding opposite ends of said side sills, a finst laterally extending intermediate sill arranged Within the front end portion of said base frame and located rearwardly of the front one of said end sills, the opposite ends of said first intermediate sill being rigidly secured to the adjacent front portions of said side sills, a front plate carried by the top front end portion of said base frame and extending longitudinally between said front end sill and said first intermediate sill and rigidly secured thereto and also eX- tending laterally between the front portions of said side sills and rigidly secured thereto, thereby to reinforce the front end portion of said base frame, a second laterally extending intermediate sill arranged within the rear end portion of said base frame and located forwardly of the rear one of said end sills, the opposite ends of said second intermediate sill being rigidly secured to the adjacent rear portions of said side sills, a rear plate carried by the rear end portion of said base frame and extending longitudinally between said rear end sill and said second intermediate sill and rigidly secured thereto and also extending laterally between the rear portions of said side sills and rigidly secured thereto, thereby to reinforce the rear end portion of said base frame, an elongated substantially rectangular floor panel of prefabricated unitary rigid sandwich structure arranged upon the top of said base frame with the lower front portion of said floor panel supported upon the top of said front plate and with the lower rear portion of said floor panel supported upon the top of said rear plate, the opposite sides of said floor panel being securely fastened to said side sills and the opposite ends of said floor panel being securely fastened to said end sills, whereby said base frame and said floor panel cooperate to produce a composite base with said floor panel lending great rigidity thereto, an upstanding laterally extending substantially rectangular heat-insulating bulkhead carried by the front end portions of said floor panel and rigidly secured thereto, said bulkhead being located approximately above said first intermediate sill, first heat-insulating structure rigidly secured to said composite base and located rearwardly of said bulkhead and cooperating mutually therewith to produce a substantially box-like body defining a lading chamber therein and provided with a pair of side doorways communieating with the opposite central sides of said lading compartment, said lading compartment being disposed above both the central portion and the rear end portion of said composite base, two pairs of heat-insulating side doors respectively mounted upon the opposite central sides of said body for pivoted movements relative thereto and with respect to said side doorways, each pair of said side doors being movable inwardly into closed positions disposed within the associated one of said side doorways and movable outwardly into open positions removed from said one side doorway, second heat-insulating structure rigidly secured to said composite base and located forwardly of said bulkhead and cooperating mutually therewith to produce a substantially box-like housing defining a plenum chamber therein that is disposed above the front end portion of said composite base, a plurality of longitudinally extending rigid structural members arranged in laterally spaced-apart relation and securely fastened to the top of said floor panel at the central and rear end portions thereof, thereby to reinforce the corresponding central and rear end portions of said composite base, said structural members being disposed in said lading compartment and cooperating with each other to define in said' lading compartment both a ladi-ng-supporting floor and a plurality of longitudinally extending and 15 laterally spaced-apart floor flues, said lading supporting floor and said floor flues being positioned above the top of said floor panel, the intermediate portions of said structural members being disposed somewhat above said side doorways arranged in lateral alignment with each other so that said lading-supporting floor and said floor fiues are continuous from end to end of said lading compartment, means for circulating air from said plenum chamber through a bottom opening provided in said bulkhead and thence rearwardly through said floor flues in said ladi ng compartment and then upwardly and back forwardly through the upper portion of said lading compartment 1 6 and ultimately back through a top opening provided in said bulkhead and thus back into said plenum chamber, and means disposed in said plenum chamber for cooling air that is circulated therethrough.

References Cited by the Examiner UNITED STATES PATENTS 2,586,893 2/52 WeJStling 62-424 XR 2,589,031 3/52 Allyne 62424 XR 3,062,156 11/62 Talmey '105423 XR CHARLES SUKALO, Primary Examiner. 

1. A REFRIGERATED FREIGHT CONTAINER COMPRISING AN ELONGATED SUBSTANTIALLY RECTANGULAR BASE FRAME INCLUDING A PAIR OF LONGITUDINALLY EXTENDING SIDE SILLS AND A PAIR OF LATERALLY EXTENDING END SILLS, THE OPPOSITE ENDS OF SAID END SILLS BEING RIGIDLY SECURED TO THE CORRESPONDING OPPOSITE ENDS OF SAID SIDE SILLS, A FIRST LATERALLY EXTENDING INTERMEDIATE SILL ARRANGED WITHIN THE FRONT END PORTION OF SAID BASE FRAME AND LOCATED REARWARDLY OF THE FRONT ONE OF SAID END SILLS, THE OPPOSITE ENDS OF SAID FIRST INTERMEDIATE SILL BEING RIGIDLY SECURED TO THE ADJACENT FRONT PORTIONS OF SAID SIDE SILLS, A FRONT PLATE CARRIED BY THE TOP FRONT END PORTION OF SAID BASE FRAME AND EXTENDING LONGITUDINALLY BETWEEN SAID FRONT END SILL AND SAID FIRST INTERMEDIATE SILL AND RIGIDLY SECURED THERETO AND ALSO EXTENDING LATERALLY BETWEEN THE FRONT PORTIONS OF SAID SIDE SILL AND RIGIDLY SECURED THERETO, THEREBY TO REINFORCE THE FRONT END PORTION OF SAID BASE FRAME, A SECOND LATERALLY EXTENDING INTERMEDIATE SILL ARRANGED WITHIN THE REAR END PORTION OF SAID BASE FRAME AND LOCATED FORWARDLY OF THE REAR ONE OF SAID END SILLS, THE OPPOSITE ENDS OF SAID SECOND INTERMEDIATE SILL BEING RIGIDLY SECURED TO THE ADJACENT REAR PORTIONS OF SAID SIDE SILLS, A REAR PLATE CARRIED BY THE REAR END PORTION OF SAID BASE FRAME AND EXTENDING LONGITUDINALLY BETWEEN SAID REAR END SILL AND SAID SECOND INTERMEDIATE SILL AND RIGIDLY SECURED THERETO AND ALSO EXTENDING LATERALLY BETWEEN THE REAR PORTIONS OF SAID SIDE SILLS AND RIGIDLY SECURED THERETO, THEREBY TO REINFORCE THE REAR END PORTION OF SAID BASE FRAME, AN ELONGATED SUBSTANTIALLY RECTANGULAR FLOOR PANEL OF PREFABRICATED UNITARY RIGID SANDWICH STRUCTURE ARRANGED UPON THE TOP OF SAID FRAME WITH THE LOWER FRONT PORTION OF SAID FLOOR PANEL SUPPORTED UPON THE TOP OF SAID FRONT PLATE AND WITH THE LOWER REAR PORTION OF SAID FLOOR PANEL SUPPORTED UPON THE TOP OF SAID REAR PLATE, THE OPPOSITE SIDES OF SAID FLOOR PANEL BEING SECURELY FASTENED TO SAID SIDE SILLS AND THE OPPOSITE ENDS OF SAID FLOOR PANEL BEING SECURELY FASTENED TO SAID END SILLS, WHEREBY SAID BASE FRAME AND SAID FLOOR PANEL COOPERATE TO PRODUCE A COMPOSITE BASE WITH SAID FLOOR PANEL LENDING GREAT RIGIDITY THERETO, AN UPSTANDING LATERALLY EXTENDING SUBSTANTIALLY RECTANGULAR HEAT-INSULATING BULKHEAD CARRIED BY THE FRONT END PORTION OF SAID FLOOR PANEL AND RIGIDLY SECURED THERETO, SAID BULKHEAD BEING LOCATED APPROXIMATELY ABOVE SAID FIRST INTERMEDIATE SILL, FIRST HEAT-INSULATING STRUCTURE RIGIDLY SECURED TO SAID COMPOSITE BASE AND LOCATED REARWARDLY OF SAID BULKHEAD AND COOPERATING MUTUALLY THEREWITH TO PRODUCE A SUBSTANTIALLY BOX-LIKE BODY DEFINING A LADING COMPARTMENT THEREIN THAT IS DISPOSED ABOVE BOTH THE CENTRAL PORTION AND THE REAR END PORTION OF SAID COMPOSITE BASE, SECOND HEAT-INSULATING STRUCTURE RIGIDLY SECURED TO SAID COMPOSITE BASE AND LOCATED FORWARDLY OF SAID BULKHEAD AND COOPERATING MUTUALLY THEREWITH TO PRODUCE A SUBSTANTIALLY BOX-LIKE HOUSING DEFINING A PLENUM CHAMBER THEREIN THAT IS DISPOSED ABOVE THE FRONT END PORTION OF SAID COMPOSITE BASE, A PLURALITY OF LONGITUDINALLY EXTENDING RIGID STRUCTURAL MEMBERS ARRANGED IN LATERALLY SPACED-APART RELATION AND SECURELY FASTENED TO THE TOP OF SAID FLOOR PANEL, AT THE CENTRAL AND REAR END PORTIONS THEREOF, THEREBY TO REINFORCE THE CORRESPONDING CENTRAL AND REAR END PORTIONS OF SAID COMPOSITE BASE, SAID STRUCTURAL MEMBERS BEING DISPOSED IN SAID LADING COMPARTMENT AND COOPERATING WITH EACH OTHER TO DEFINE IN SAID LADING COMPARTMENT BOTH A LADING-SUPPORTING FLOOR AND A PLURALITY OF LONGITUDINALLY EXTENDING AND LATERALLY SPACED-APART FLOOR FLUES, SAID LADING SUPPORTING FLOOR AND SAID FLOOR FLUES BEING POSITIONED ABOVE THE TOP OF SAID FLOOR PANEL, MEANS FOR CIRCULATING AID FROM SAID PLENUM CHAMBER THROUGH A BOTTOM OPENING PROVIDED IN SAID BULKHHEAD AND THENCE REARWARDLY THROUGH SAID FLOOR FLUES IN SAID LADING COMPARTING AND THEN UPWARDLY AND BACK FORWARDLY THROUGH THE UPPER PORTION OF SAID LADING COMPARTMENT AND ULTIMATELY BACK THROUGH A TOP OPENING PROVIDED IN SAID BULKHEAD AND THUS BACK INTO SAID PLENUM CHAMBER, AND MEANS DISPOSED IN SAID PLENUM CHAMBER FOR COOLING THE AIR THAT IS CIRCULATED THERETHROUGH. 